The present invention relates to a method for performing hemming with respect to a workpiece, using an appropriate hemming die, and to a system for performing hemming.
A system shown in FIG. 12 is used in hemming the peripheral part of an outer panel and an inner panel of a part of an vehicle body such as a trunk lid or door panel, with the inner panel and the outer panel held together by an adhesive, thereby bending the peripheral part of the outer panel.
The vehicle body part that is the workpiece is hemmed at a hemming station 1 at which is fixed a hemming die D (D.sub.1). On the side of this hemming station 1 is disposed a die storage area, in which hemming dies D (D.sub.2, D.sub.3, D.sub.4, and D.sub.5) for accommodating various other workpiece types.
In the storage area 3, a hemming die D can move to the left and to the right as shown in the drawing, and at a position corresponding to the hemming station 1 it can also move between the die storage area and the hemming station 1. By enabling this movement, it is possible to interchange a hemming die D with a desired die to accommodate a specific type of workpiece.
At a station 5 of the hemming station 1, cylinder operations for applying adhesive to hold the inner and outer panels together and for performing mutual positioning of the panels is successively performed. After a workpiece, made up of the two panels adhered to one another, is transported to the hemming station 1, it is transported out to the station 7. The transport of the workpiece into the hemming station and away therefrom is performed by a conveyer (not shown in the drawing).
FIG. 13 shows another type of hemming system, which performs hemming of the wheel housing arch part of a vehicular body side, in which case the workpiece is transported along the production line 9 in the direction of the arrow A in an upright attitude, with the roof rail upward and the side sill downward.
A plurality of hemming stations provided with hemming dies corresponding to various types of workpieces for various vehicle types and fixtures for holding these hemming dies in position are disposed to the side of the production line 9. A transport robot 13, which holds a workpiece on the production line 9 and transports the workpiece toward a hemming station 11 is movable in a direction along the alignment direction of the plurality of hemming stations 11, and moves the held workpiece toward an appropriate hemming station 11, at which point the workpiece is positioned and held in place.
FIG. 14 is a plan view showing, at the hemming system shown in FIG. 13, the condition in which a hemming die 17 hems the wheel housing arch part 15a, and FIG. 15 is a perspective view of FIG. 14 in the direction of the arrow B. The hemming die 17 is continuously held by a hemming die driver 21 that is fixed to a base plate 19, and the body side 15 is held and fixed at a number of positions around the periphery thereof by a plurality of clamping mechanisms 23 disposed on the base plate 19.